Agua de Piedra Creek, an intermittent stream, rises five miles southeast of Adrian in southwestern Oldham County (at 35°16' N, 102°46' W) and flows northwest for thirteen miles to its mouth on Trujillo Creek (at 35°26' N, 102°53' W). The streambed runs across flat terrain with some moderately steep slopes. The soils, shallow to moderately deep silt loams and loose sand, support brush, mesquite, and grasses. The Spanish name means "stony water." The stream is in the heart of a vast ranching area, successively part of the LE, XIT, and Matador ranches.